Coaxial line coupling



sept. 2s, 194s.

G. c. DEvoL comm LINE courmne 2 Sheets-Sheet 1 Filed Feb. 4, 1943 ltlllbllillllllllllbl G. c. DEVOL CoAxIAL LINE couPLmG spf. 28, 194s.

2 Shets-Sheet 2 Filed Feb. 4, 1943 J// I lll Patented `Sept. 1948 I OOAXIAL LINE COUPLING George C. Devol, Greenwich. Conn.,"'auignor to e Sperry Corporation, a corporation of Dela- I Appueaucn February 4, 194s. serial No. '414,740 I 1s claim. (ci. 17e-sa) This invention relates to couplings for eleotrical transmission lines and is more particularly concerned with couplings for ilexible transmission lines of the coaxial conductor type.

The major object of this invention is to provide a coupling for a ilexible transmission line of the coaxial conductor type wherein the coaxial conductors are reliably and securely yattached in a novel manner to the coupling.

A further object ofthe invention is to provide novel rigid coupling construction for a flexible transmission line of the coaxial lconductor type.

It is a further object of the invention to provide a coupling structure for a flexible coaxial conductor transmission line wherein novel clamp arrangements are provided between the outer conductor and the coupling.

A further object of the invention is to provide a novel coaxial conductor transmission line coupling wherein the end of such a ilexlble line is rigidly wedged between suitable relatively adjustable inclined surfaced coupling members.

A further object of the invention is to provide a coaxial conductor transmission line coupling having novel arrangements for connection to the inner and outer line conductors.

Further objects of the invention will presently appear as the description proceeds in connec- .tion with the appended claims and the annexed' drawings wherein: Fig. 1 is an axial section through a coaxial transmission line provided with a coupling according to the invention; Fig. 2 is an exploded view illustrating various elements of the coupling and the mode of as sembly of the coupling with the ilexible line in Fig. 1.

Fig. 3 is an axial section through a coaxial transmission line provided with a coupling of somewhat diierent structure than Fig. 1, but' embodying the invention;

Fig. 4 is an exploded view illustrating various elements and the mode of assembly of the line of F18. 3; and

Fig.' 5 is an axial section through a coaxialtransmission line illustrating a still further embodiment of the invention.

erties for' the use desired, an outer conductor I3 which is usually of braided copper to permit desired expanslbility and flexibility, and an external insulator covering I4 of rubber or saturatedfabric o! any known design.

The coupling consists primarily of line terminal sections indicated at l5 and a body member IB. Each line terminal section comprises a tubular fitting I1 having a radially projecting flange I l at one end, an intermediate threaded section I9, and a tapered or substantially frustoconical section 2l at the other end. As shown in Fig. 1, section 2l projects at least partly within the open end of the transmission line. Since the tapered face of section 2l is of increasingly larger outer diameter than conductor I3, th latter is outwardly flared at its end.

Internally, iltting l1 is formed with a cylindrical bore 22 into which extends the line insulator sleeve 'I2 as illustrated. A section cf the sleeve is cut away to bare inner conductor Il in a tip 2l, which is preferably rounded oil for coupling purposes.

A hollow substantially truste-conical metal collar 24. preferably internally of the same taper as section 2l, is disposed at least partly between outer conductor I3 and insulator covering I4 at the open end of the line. This ares covering I4 outwardly as illustrated. Finally, an externaiholding member 25, internally threaded at one end to be rotatably `adiustably mounted on section I9 of fitting l1, extends over the joint and is formed with an internal substantially truste-conical surface 26 preferably of the same taper as the outer surface of collar 24. Beyond surface 28, the bore of holding member 25 ts relatively snugly about the transmission line. lWhen holding member 25 and fitting I1 are relatively rotated to draw them together, the flared end of insulator covering I4 is tightly compressed between surface 2l and collar 24, and simultaneously the outer conductor is tightly gripped between collar 24 and iltting I1. As is shown in Fig. 1, a relatively large annular area of insulator covering I4 is clamped in the coupling. Similarly, a relatively large annular area of outer conductor I3 is clamped Ibetween collar 24 and the tapered metal face at 2l on fitting I1, thereby insuring an excellent conductive connection between vconductor i3 and fitting AI1. These large clamping areas `afford strength against longitudinal pull on the transmission line.

Body member II comprises a tubular metal part vServing as a continuation of the outer oonlwith rigid, preferably integral,

ductor of the transmission line. An enlarged central iiange 21 is formed to be gripped by a wrench or the like and flanked by external threaded portions 28 for mounting nuts 29. Each nut 29 is formed with a radially inwardly pro- `iecting flange 3l for engaging flange I3 on the adjacent fitting l1, so that when either nut 29 is drawn tight, the adjacent tting I1 is secured tightly to body member i6.

Body member I 8 is formed at opposite ends longitudinally projecting cylindrical collars 32 each of which extends with friction fit into a suitable shouldered region 33 of fitting bore 22. 'I'his provides a telescoping connection between the fitting and body member, promoting ease of assembly.

Internauy, body I contains an insulator sleeve 34, which may be of solid or flexible dielectric material as desired, and a central hollow metal tube 3B which is preferably fixed to the sleeve 34. Sleeve 3 is of such length as to extend entirely through the body member and `collars 32, and preferably a short distance beyond collars 32 as illustrated.

Tip 23 fits frictionally within the female fitting provided by open ended tube 35, thereby providing a good electrical connection to inner conductor il. The parts are furthermore so dimensioned that, in the assembly illustrated, the adjacent ends o insulator sleeves @il and i2 are closely adjacent and preferably abutting.

As shown in Fig. the lef-t side of the coupling is identical with that above described if a lief-:ible line is to be attached thereto. If, however, the coupling is for attaching e. flexible line to a rigid transmission line, the coupling may be altered to suit at the lef-t side.

The manner of assembling the coupling is shown best in Fig. 2. Holding member i5 is lrst ippedover the cable end, which is suitably out to expose conductor il and remove the necessary sections of sleeve i2, outer conductor i3 and covering Collar 2d is then inserted strongly between covering i@ and the outer conductor i3. whereby covering iii is rubber, it stretches easily to permit this operation. Then fitting il, which has nut EG slipped thereover as shown in Fig. 2, is advanced so that section 2i is inserted between the outer conductor i3 and sleeve i2, sleeve i2 simultaneously advancing within bore 22. Holding member 25 is then moved up intothreaded engagement with fitting i1 and the two are drawn tight, thereby clamping the flexible line to fitting il' as abovedescribed. The length of tip 23 is so chosen as to terminate adjacent the open end of tting il as illustrated.

Fitting il is then rigidly attached to body member i6 by first telescoping collar 32 into shoulder 3S and then drawing nut 29 up tight. During this operation, tip 23 enters tube 35, and the insulator sleeves i2 and 34 are drawn into substantially abutting relation.

In Fig. 3. the illustrated exible line is of the type having the inner conductor Il supported by successive, individually rigid, universally coupled insulator beads 33 of polystyrene or the like. Fitting 31 is mainly similar to fitting I1. Fitting 37 has an externally threaded section 38 for mounting holding member 25, and a frusto-conical end portion 39 projecting within outer conductor i8. When holding member 25 is drawn tightly, the flexible line is clamped to fitting 31 as in Fig. 1.

The manner of attaching fitting 31 to body member 4l is somewhat different from Fig. 1.

Body 4I is formed with a wrench-fitting flange 42 and externally threaded end sections 43. At each end, body member 4l i5 formed with an inwardly tapering throat 44 which terminates in a cylindrical shoulder 4l. An elongated cylindrical collar 43, rigid and preferably integral with i'itting 31, projects within the body member 4| and has its end seated in shoulder 45. A preferably rigid insulator sleeve 40 is supported by fitting 31 wherein it terminates well short of the flexible line end as shown and extends through collar 48. Sleeve 40 is internally shouldered at 50 for a reason which will appear. A slidable locking sleeve 41 is mounted on collar 46. Sleeve 41 is formed with an outwardly tapered, preferably conical, face 48 adapted to be engaged by a similarly shaped internal face 43 on a nut 5| threadedly mounted on section 43 of the body member.

Within body member 4| is a rigid insulator block 52 carrying a hollow metal tube 53 which projects therefrom at opposite ends and serves as an inner line conductor extension in the assembly.

For assembly, as shown in Fig. 4, a much longer section of inner conductor i i is bared than in Fig. 2. This` is became conductor Il must extend through insulator sleeve 40. Preferably enough beads 36 are left on conductor Il to insure substantial abutment with sleeve 0 within fitting 3'?, as shown in Fig. 4.

Sleeve 41 and nut 5l are placed on collar 46, which is then inserted into body member 4|. As nut t is drawn up tight, sleeve 41 is slidably advanced by Contact of faces 48 and 49 and wedged into tapered bore 44. 'if desired, the end of sleeve el may be weakened at Sii to facilitate this action and help strengthen the wedged connection between the fitting and body member. During this operation also, the projecting end of tube 53 extends into shoulder 50, While tip 23 of the inner conductor slips frictionally into tube 63. The end of sleeve 4U is drawn closely adjacent the associated end of block 52.

The left side of Fig. 3 is preferably substantialy identical, as illustrated.

The assembly of Fig. 5 is similar to that of Fig. 3 in the manner in which the flexible line is attached to fitting member Bi, as illustrated, conical section 62 being clamped to the outer conductor when holding member 25 is tight. Here, however, sufficient beads 36 are retained on conductor Il to extend entirely through hollow fitting 3i, so that tip 23 projects from the fitting.

Body member 63 is externally similar to body i in Fig. 3 and contains a rigid insulator sleeve 64 to which is fixed a hollow tube 65. Sleeve 64 extends almost entirely through the bore of body 63, which bore is formed at each end with conical locating recess G3 for receiving correspondingly formed projection 61 on the fitting. Fitting 6i is provided with a radial end flange 68 for engagement with a similar flange 69 on a nut 10.

When nut 10 is drawn tight, fitting 6I and body member B3 are drawn tight, surfaces 66 and 61 insuring coaxial alignment, and tip 23 enters tube 85. As illustrated, the left side of Fig. 5 may be identical with the right side.

I have thus provided couplings for flexible coaxial type transmission lines which are mechanically strong and electrically reliable. The inner conductor of the line is joined to the inner conductor of the coupling with very little change in diameter through the fitting to prevent sudden or large changes in characteristic impedance in the coupling. 'Ihe outer conductor is held by pressure contact, without solder, through the coupling, thereby providing strength against axial pull. In each instance the dielectric in the line, between outer and inner conductors, is butted under compression to the corresponding dielectric in the coupling, for retaining electrical characteristics of the line in the coupling. The insulator sleeve in the line, solid or beaded, is guided into the associatedcoupling member during as'- sembly. The inner conductor tip 2l is protected against bending by termination short of the far end of the clamp fitting into which the line extends.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a -limiting sense.

What is claimed is:

1. In a coupling adapted for straight through extension of a flexible transmission line having an inner conductor,.a substantially coaxial outer conductor and an insulator covering about said outer conductor; the combination comprising a coupling member having a clamping face adapted to` extend within said outer conductor, a clamp collar adapted to be inserted between said outer conductor and said covering, a holding member adjustably connected to said coupling member for tightly securing said outer conductor between said clamping face and said clamp collar and for securing said insulator covering between said holding member and said clamp collar, and conducting means coaxially supported within said coupling member and adapted to telescopically receive said inner conductor.

2. In a coupling for a flexible transmission line having a solid inner conductor, a substantially coaxial outer conductor and an insulator covering about said outer conductor; the combination comprisng a tubular coupling member having a generally frusto-,conical face adapted to be inserted into the open end ofsaid line interiorly of said outer conductor, said coupling member also having a bore equal to the -inner diameter of said outer conductor and forming a smooth extension thereof, a substantially frusto-'conical clamp collar adapted to be inserted intok the open end and said outer conductor so that outer conductorv is flared at its end, said viitting being hollow to receive a substantial length lof the end section of said insulator sleeve, a substantially frusto-conical movable clamp'collar adapted to be inserted into the open end of said line between the outer conductor and said covering so that said covering is flared at its end, and a solid external holding member adjustably connected to said fitting having an internal face adapted to bear against said covering, said tubular fitting, said clamp collar, and said holding member having 'clamping surfaces at least partly coextensive with one 'another so that said outer conductor and coveringrmaybe securely clamped in said coupling upon adjustment of saidr holding member and conducting means coaxially supported within said fitting and adapted to telescopically receive said inner conductor. "l

5. In a coupling for an ultra high frequency electrical transmission line having a solid inner conductor, a substantially coaxial outer conductor, an insulator means between said conductors, and an insulator covering about said outer, conductor; a tubular fitting, movable gripping means within said coupling for clamping said outer Vcon'-v ductor and said insulator covering securely to said fitting, said tting being centrally apertured to receive the extended end of said insulator means, a coupling body member containing an insulator sleeve and a fixed center conductor therein having a female end, and means for securing said fitting and body member together for electrically continuing said outer conductor, with the end of the insulator sleeve of said body member closely adjacent the associated end of the insulator means of said line, and with said inner line con.

of said line between said outer conductor and said covering, a holding member adjustably connected to said coupling member, said tubular coupling member, said clamping collar, and said holding member having clamping surfaces at least partly coextensivewith one another and conducting means coaxially supported within said tubular coupling member and'adapted to telescopically receive said inner conductor, whereby smooth continuations of said inner and outer conductors are provided.

3. The coupling defined in claim 2, wherein said holding member is provided with an internal substantially trusto-conical face adapted to engage saidcovering exterior-ly and opposite said collar. 4. In a coupling for a flexible transmission line having a solid inner conductor, a substantially coaxial outer conductor. an insulator sleeve between said conductors andan insulator covering aboutv said outer conductor; the combination comprising a tubular fitting having a substantially posite ends and said securing means comprises threaded connector collars enclosing the joint between said fitting and body member.

l0. In a coupling for interconnecting two flex ible transmission lines ofthe coaxial type, a rigid body member, clamp fittings by which the outer conductors and insulation covering, respectively, of said lines are adapted to-be separately gripped said fittings connecting substantially telescopto provide smooth electrical continuity of the outer and inner conductors of said lines.

11. In a coupling for a flexible transmission line of the type having coaxial inner and outer conductors spaced by insulating means' and having an insulator covering about said outer conductor, the combination comprising a coupling member having a clamping face adapted to extend within said outer conductor and having a central recess adapted to receive said insulating audaces means, a holding member adjustable' connected to said coupling member for securing` said outer conductor and said insulator covering between said holding member and said coupling member, a hollow body member forming the outer ccnduc= tor in said coupling, an insulator sleeve extending entirely through said body member, and a tubular inner conducting,1r member fined within said in sulator sleeve, said insulating means extending into said coupling member a sufilcient distance to abut said insulator sleeve, and said tubular inner conducting member sliding over the ends of the inner conductors of said transmission line.

l2. In a coupling between a nrst transmission line and a second transmission line, said two lines having respective inner conductors and hollow outer conductors oi substantially the same inner diameter respectively concentrically disposed about said inner conductors; the combination comprising coupling means adapted to be inserted into the open end of said nrst line and extending between said irst and said second lines, and a holding member adjustable; connected to said coupling means for clamping said first line to said coupling means, said coupling means having a continuous inner bore completely therethrough of the same diameter as the bore or" said outer conductors and providing smooth electrical con= tinuity therebetween.

13. In a coupling for a flexible transmission line having an inner conductor, a coaxial 'outer conductor, and an insulator covering about said outer conductor, the ratio of the inner diameter of seid outer conductor to the outer diameter or" said inner conductor being of a iixed predetermined value; the combination comprising a coupling member adapted to contact said outer conductor, a holding member adjustably connected to said coupling member and adapted to contact said insulator covering, and clamping means formed in said coupling and having a continuous inner bore completely therethrough of the same diameter as that of said outer conductor, thereby providing an effective extension of said outer conductor and maintaining said diametre] ratio substantially constant, said clamping means being operable to secure said outer conductor and said insulator covering to said coupling.

14. In a coupling for a flexible transmission line having an inner conductor, a. coaxial outer conductor, and an insulator covering about said outer conductor; the combination comprising a pair of adiustably interconnected tubular coupling members having clamping faces between which said line is adapted to be introduced, one of said coupling members being telescopingly insertable within said transmission line between said inner and outer conductors, the other of said coupling members being disposed exteriorly of said insulator covering, an axially displaceable adapter interposed between said outer conductor and said insulator covering and operable upon adjustment of said coupling members to separately grip said outer conductor and said insulator coverina and to bind them securely to said couplincf members, and a conducting member coaxially supported within one ol said coupling members and adapted to contact said inner conductor and to provide an extension thereof.

l5. in a coupling for a iiexible transmission line having an inner conductor, a substantially coaxial outer conductor, and. an insulating cover surroun ng said outer conductor; the combina.- tlon con ri trg a coupling member having a substan/cialis7 conical clamping face insertable within said transmission Eine in contact with said outer conductor, a holding member adjustably connected to said coupling member and having a clamping face adapted to contact said insulating cover, axially movable gripping means in said coupling having clamping faces adapted to oppositely engage said outer conductor and said insulating cover, said clamping faces being operable to separately grip said outer conductor and said insulating cover upon adjust-nient of said holding member relative to said coupling member and a conducting member coaxlally supported within said coupling member and adapted to contact said limer conductor and to provide an extension thereof.

GEORGE C. DEVOL.

REFERENCES CITED The :Tollowing references are of record in the rile o' this patent:

UNITED STATES PATENTS Number Name Date 477,951 Mezger June 28, 1892 1,060,600 Jamieson May 6, 1913 1,246,964 Lowe Nov. 20, 1917 1,497,002 Sanderson June 10, 1924 1,718,817 Greene June 25, 1929 1,896,444 Fossati Feb. 7, 1933 2,007,357 Anderson et al July 9, 1935 2,093,403 Sertillange Sept. 21, 1937 2,118,103 Oeding May 24, 1938 2,173,643 Moser Sept. 19, 1939 2,275,762 Horton Mar. 10, 1942 2,296,766 Bruno Sept. 22, 1942 2,328,111 Thornbery Aug. 31, 1943 FOREIGN PATENTS Number Country Date 112,951 Great Britain Feb. 7, 1918 304,007 Great Britain Jan. 17, 1929 489,510 Great Britain s- July 28, 1938 590,808 France July 19, 1923 

